Figure 1. Sankey diagram for the world, 2002.
Source: WADE 2003 (data derived from International Energy Agency)

CHP, on-site renewable energy and energy recycling are the three cornerstones of WADE’s research and advocacy programmes. These are high-efficiency solutions that recover heat and substantially reduce network losses. A glance at Figure 1, a Sankey diagram for the worldwide electricity sector, highlights the potential of these three decentralized energy (DE) solutions. It reveals the great bulk of energy that is lost in the process of conversion, transmission and supply to the end consumer. According to a WADE analysis of data from the International Energy Agency, waste of energy from the worldwide electricity system is around 67% – that’s two thirds.

The picture is very similar for virtually all other countries. Most of the losses are from central thermal plants that cannot recover and use the waste heat. Considerable losses also arise from transmission of the energy from producer to consumer.


Figure 2. Oil reserves-to-production (r/p) ratios.
Source: Annual Statistical Review of Energy, 2004, BP

To grasp the mind-boggling scale of the wastage, consider this: the energy lost in the worldwide electricity system is equivalent to the total energy consumed by the worldwide transportation sector. Madness, isn’t it?

While the rationale for central generation has been sound in the past, there is no longer any technical or economic justification to proceed down the same path in the future. Nor should we for other reasons. Energy efficiency, the shy child that everyone has ignored for 30 years, is about to trip us up so that, finally, we do take notice once and for all.

This is a one-way bet and these are the reasons why.




UK-based ENER·G has completed the installation and commissioning of a trigeneration packaged energy system for the Driver Vehicle and Licensing Agency (DVLA) in Swansea, Wales. The new system has the capacity to reduce dramatically DVLA’s energy consumption and carbon dioxide emissions.

Specified following a competitive tender, ENERoG has provided a containerized trigen system, featuring a 1 MW CHP unit and a 700 kW absorption chiller. These systems operate seven days a week, providing electricity, medium temperature hot water (MTHW) and chilled water (CHW) to the site.

The ENER·G 1150 natural gas-fired CHP unit recovers heat from both the engine cooling circuit and from the exhaust gases, enabling it to provide 1400 kW of heat at full output. The unit also delivers 1150 kW of electrical power at 100% output and is configured to match the electrical demand of the site, thereby preventing the export of excess power to the grid.

The absorption chiller is driven by hot water to complement the three existing 1.2 MW electrical chillers. This enables high utilization of the CHP heat output during warm periods when there is a small demand for heating and hot water, but when cooling demand is high, fuel savings to DVLA is maximized.

All the main plant is located externally in a compact area previously used for standby generators. The scheme is financed by ENER·G with investment recovered via the company’s Discount Energy Purchase (DEP) scheme. The DEP scheme is based on a sliding, variable scale dependent upon the level of generation of the CHP unit – the more the unit is able to run at full output, the lower the DEP rate.


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